20 by 10 feet high (fig. 3), where a flow- 

 control system designed to minimize turbu- 

 lence produces a relatively uniform flow at 

 any depth up to 4 feet in the tank. 



Designed for a variety of large-scale 

 hydraulic conditions, channel width ccUi be 

 varied by the installation of false walls 

 (fig. 4). This permits channel widths up 

 to 20 feet, depths to 4 feet, velocities 

 to 4 feet per second (faster when channel 

 width is reduced), auid discharge rates of 

 10, 20, 30, and 40 cubic feet per second 

 using 1 to 4 pumps in combination. The 

 tank is also used as a pool (fig. 5). A 

 coating of asphalt on the walls cUid floor 

 insulates against electrical grounding and 

 permits tests using electrical fields in 

 water (fig. 5). 



To maintain flexibility there are no 

 permanent installations in the tank proper — 



only the flow-control system in the headbox 

 and stop-log guides between the tank and 

 sump (fig. 6, page 4). 



Six-foot areas on each side of the 

 tank allow passage space for personnel, 

 limited storage, additional small experi- 

 mental tanks, aind troughs for temporary 

 fish-holding. A large deck over the sump, 

 continuous with the walkways, provides 

 space for heavy machinery of a more perma- 

 nent nature, such as the 4 large pumps. 



Other experimental areas 



Two separate laboratory areas provide 

 space for other types of studies. The 

 larger of these is a wing on the main 

 structure (fig. 1) which includes severcil 

 general-purpose tanks, provisions for chem- 

 ical analyses, sink and refrigerator, 



Figure 4. — Main tank with a 5-foot channel 

 used in a study of the effect of 

 sonic tags on swimming ability 

 and behavior of adult salmonoids. 



Figure 5. — The main tank as used in studies 

 of electrotactic response of adult 

 squawfish. An electrode eirray was 

 enclosed within the tauik and was 

 energized by the generator and 

 electronic pulse unit on the deck. 



